This invention relates to pressurized gas-entrained particulate feed systems, and particularly to systems where feed rate is determined from differential measurements of a particulate supply container.
In certain steelmaking processes, flux materials such as limestone, burned lime, or fluorospar, may be introduced into the steelmaking vessel by injecting them in powdered form, entrained in a pressurized refining gas. A system for controlling injection of fluxes to be introduced in this manner is shown in U.S. Pat. No. 4,136,857 Kolb. In this system, the flux feed rate is measured by differential weight of the feed hopper, as indicated by load cells mounted between the hopper and its supports.
The feed rate measurements have been subject to some degree of error, generally attributed to load cell inaccurracy, valve movement and other unknown factors. The primary cause of error was not readily apparent, although it was recognized that the degree of error varied generally in proportion to operating gas pressure. Efforts have been made to eliminate the effect of valve movement by providing sturdier supports, but these have not been notably successful.
It is a primary object of this invention to provide an improvement in pressurized gas-entrained particulate feed systems substantially eliminating errors in flow rate measurements caused by deviations in differential weight measurements of a container for holding a supply of the particulates.